1. Field of the Invention
The present invention relates to a processing method and a processing apparatus for a computer system, more particularly, to an interrupt processing method and an interrupt processing apparatus for a computer system having a central processing unit and a plurality of peripheral units (peripheral equipment), wherein an interrupt request signal is transferred from each peripheral unit to the central processing unit, and an interrupt acknowledge signal in response to the interrupt request signal is successively propagated from the central processing unit to each peripheral unit by a daisy chain connection.
2. Description of the Related Art
In the prior art, an interrupt processing is carried out, for example, by using a daisy chain connection constructed by a plurality of peripheral units. An interrupt request signal is output from each peripheral unit to a central processing unit through a signal conductor, and when the central processing unit receives the interrupt request signal and an interrupt processing is enabled, the central processing unit outputs an interrupt acknowledge signal to the peripheral unit by using a daisy chain connection. Namely, the central processing unit first outputs the interrupt acknowledge signal to a first step peripheral unit, and if the first step peripheral unit does not output the interrupt request signal, the interrupt acknowledge signal is propagated to a secodn step peripheral unit, i.e., a next step peripheral unit. Therefore, as described above, the interrupt acknowledge signal is successively propagated to each peripheral unit. When the interrupt acknowledge signal is , propagated to the specific peripheral unit which has output the interrupt request signal, the specific peripheral unit outputs a vector address to the central processing unit through a data bus, so that an interrupt processing routine for the specific peripheral unit is started. Note, the above peripheral units may be not only input-output devices or auxiliary storages, but also interrupt controllers. The input-output device or auxiliary storage is, for example, a cathode ray tube display, an optical mark reader, and a hard disk drive device, etc. The interrupt controller, which is used as an interrupt handler or an interrupt generator, controls a plurality of input-output devices or auxiliary storages.
Note, if noise exists in the signal conductor in which the interrupt request signal is transferred, this noise may be taken as the interrupt request signal in the central processing unit. In this case, the central processing unit outputs an error interrupt acknowledge signal, without receiving a correct interrupt request signal. Therefore, none of the peripheral units outputs a response signal to the central processing unit, and thus the central processing unit is held in a response waiting state and the processing is unnecessarily delayed.